Valves may be employed in any one of numerous situations. For example, valves may be used in an air distribution system to allow, control, or shut off airflow from one portion of an aircraft's ducting to another. In this regard, pneumatic valves may be disposed in a duct between an air source and one or more outlets to control the flow of the received air that is distributed to other components or areas in the aircraft, such as, for example, the environmental control system or an aircraft cabin.
One exemplary type of pneumatic valve that has been employed in aircraft is a butterfly valve. A butterfly valve is typically made up of a valve flowbody and a butterfly plate. The valve flowbody may be made of a rigid material, such as metal, and includes a channel or bore therethrough, defined by an inner surface. The valve flowbody is configured to be disposed between two ducts or disposed in a portion of a single duct. The butterfly plate is made of a rigid material as well and is rotationally mounted to the valve flowbody. Conventionally, the butterfly plate is positioned in the channel such that a minimum clearance is formed with the inner surface of the valve flowbody. An actuator and a spring may be used to control the rotation of the butterfly plate.
Typically, the butterfly plate is moved between closed, open, and partially open positions. When in the closed position, where the butterfly plate is perpendicular or near perpendicular in the flowbody bore, the butterfly plate substantially blocks the channel to prevent, or at least inhibit, fluid from flowing therethrough. When fluid flows through the valve flowbody in a forward direction, the butterfly plate moves to the open or partially open position to allow fluid flow through the channel. To provide for sealing of the butterfly valve plate relative to the channel, the butterfly valve plate includes a sealing ring groove about a periphery into which is seated a sealing ring. During rotation of the butterfly valve plate, the sealing ring engages the channel wall, and provides sealing about the periphery of the butterfly valve plate. The sealing ring must be properly positioned during installation and maintained in proper alignment with respect to the periphery of the butterfly valve plate to achieve adequate sealing effects. During operation of the valve, the sealing ring has a tendency to expand outwards from the butterfly valve plate when under the influence of a pressure. More particularly, when the butterfly valve plate is in an open position, the sealing ring is not in direct contact with the channel and may come out of the sealing ring groove into which it is positioned. In particular, the flow of fluid through the channel may cause a downstream portion of the sealing ring to expand and become misaligned relative to the sealing ring groove. When the butterfly valve plate is then closed, increased closing forces may exist as a result of the misaligned sealing ring. In some cases, the misaligned sealing ring may prevent the butterfly valve plate from fully closing when the sealing ring becomes lodged between the periphery of the butterfly valve plate and the channel.
Accordingly, there is a need for a butterfly valve plate sealing assembly that includes a means for constraining a sealing ring within a sealing ring groove with limited expansion of the sealing ring. More specifically, there is a need for a means to minimize misalignment of the sealing ring from within the sealing ring groove when the valve is pressurized. In addition, it would be desirable for the sealing assembly to be relatively inexpensive to implement. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.